| Resistive random access memory(RRAM)devices with memristive characteristics are considered to be the most promising next-generation new nonvolatile memory to replace traditional silicon-based flash memory due to its simple structure,strong scalability,and excellent performance.Organic resistive switching memory(ORSM)based on organic resistive switching(RS)materials has a broad development prospect in the field of memory devices due to its advantages of simple film-forming method,flexibility and low cost compared with inorganic materials.The donor-acceptor(D-A)binary system based on organic conjugated molecules is a common organic function material system.By solution method,the RS layer of ORSM can be spin-coated into a film,and the concentration ratio between the matrix and the guest material can be modulated to control the memory characteristics.However,D-A based ORSM has limitations in regulating the electrical performance of the multi-stage resistance or improving the stability of the device.Therefore,this paper mainly focuses on the research of ternary doping in improving the performance and stability of binary ORSM devices,and also studies the RS mechanism of ternary devices.The research contents and results are as follows:(1)The shadow mask design and test environment optimization of ORSM devices were studied.A set of device test platform in nitrogen environment was designed.The preparation method of ORSM device based on the organic composite film prepared by the solution method was summed up,and it was optimized according to the actual experimental condition.(2)D-A binary ORSM devices(ITO/PVK: OXD-7/Al)and D-A-A ternary ORSM devices(ITO/PVK: OXD-7: PBD/Al)with different acceptor concentrations have been successfully prepared.We have studied the influence of doping different acceptor concentrations on the electrical properties of binary and ternary ORSM devices.Both binary and ternary devices with appropriate acceptor concentrations exhibited reversible bipolar RS characteristics.Among them,the ternary devices blended with a certain amount of PBD exhibited ternary RS behavior.The ON/OFF ratio of the ternary devices doped with PBD was effectively improved compared to the binary devices.The research results showed that the improvement of the electrical performance of the ternary device is mainly attributed to the blend of an appropriate amount of acceptor PBD.In fact,the conduction mechanism of ternary ORSM blended with PBD is due to the charge transfer between different level depth traps in D-A-A system(3)Bipolar materials Dp An-In Ac and Dp An-5Bz Ac were doped into the active composite film of D-A system PVK: OXD-7 with different concentrations to prepare ORSM devices.The appropriate doping could effectively improve the electrical performance and reliability of the device.Characterization results revealed that bipolar materials both have good electrochemical stability and excellent film-forming properties,which make the devices doped with bipolar materials obtain good retention,endurance and uniformity,and showed more superior RS stability than those of the binary devices.The RS mechanism of the ternary device doped with bipolar materials are due to the charge transfer between PVK and OXD-7,and the doping of bipolar materials reduced the "hopping" barrier of carriers,which benefits the charge transfer between PVK and OXD-7 and effectively decrease of operating voltage.The results show the influence of ternary doping of acceptor(PBD)and bipolar(Dp An-In Ac/Dp An-5Bz Ac)small molecular materials on the performance of D-Abased ORSM devices,which provides a new research dimension for the design and development of future ORSM devices. |
PDF Full Text Request